Disk drive with balance plug having longitudinal retainers

ABSTRACT

Described herein is a disk drive balance plug that includes a substantially cylindrical body defining a first end, a second end, a substantially cylindrical outer surface, and a plug central axis. The balance plug also preferably includes at least one protrusion extending along the cylindrical outer surface between the first and second ends in a direction substantially aligned with the plug central axis.

BACKGROUND

Hard disk drives, (HDD) are often used in electronic devices, such ascomputers, to record data onto or to reproduce data from a recordingmedia, which can be a disk having one or more recording surfaces. TheHDD also includes a head for reading the data on a recording surface ofthe disk and for writing data unto one of the surfaces. An actuator isprovided for moving the head over a desired location, or track of thedisk.

The HDD includes a spindle motor for rotating the disk during operation.When the disk drive is operated, and the actuator moves the head overthe disk, the head is floated a predetermined height above the recordingsurface of the disk while the disk is rotated, and the head detectsand/or modifies the recording surface of the disk to retrieve, record,and/or reproduce data from and/or onto the disk.

When the HDD is not in operation, or when the disk is not rotating, thehead can be rotated by the actuator to a position such that the head isnot over the disk or the recording surfaces. In this non-operationalconfiguration, the head is “parked off” of the recording surface of thedisk.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of thedisclosure will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the disclosure and not to limit the scope of thedisclosure. Throughout the drawings, reference numbers are reused toindicate correspondence between referenced elements.

FIG. 1 depicts a perspective view of a disk drive in accordance with oneembodiment.

FIG. 2 illustrates a top view of a disk drive in accordance with oneembodiment.

FIG. 3 illustrates a perspective view of a disk clamp in accordance withone embodiment.

FIG. 4 illustrates a top view of a disk clamp in accordance with oneembodiment.

FIG. 5 illustrates a partial cross-sectional view of a disk pack inaccordance with one embodiment.

FIG. 6 illustrates one embodiment of a balance plug.

DETAILED DESCRIPTION

Referring now to FIG. 1, there is depicted an exploded perspective viewof a disk drive 10 according to embodiments described herein. The diskdrive 10 includes a head disk assembly (HDA) and a printed circuit boardassembly (PCBA). The head disk assembly includes a disk drive housinghaving disk drive housing members, such as a disk drive base 12 and acover 14. The disk drive base 12 and the cover 14 collectively house atleast one disk 16. A single disk or additional disks may be included inthe disk drive.

The disk 16 includes an inner diameter (ID) 18 and an outer diameter(OD) 20. The disk 16 further includes a plurality of tracks on itsrecording surface, or face, for storing data. The disk 16 may be of amagnetic recording type of storage device, however, other arrangements(e.g., optical recording) may be utilized. The head disk assemblyfurther includes a spindle motor 22 for rotating the disk 16 about adisk rotation axis 24. The head disk assembly further includes a headstack assembly 26 rotatably attached to the disk drive base 12 inoperable communication with the disk 16. The head stack assembly 26includes an actuator 28.

The actuator 28 includes an actuator body and at least one actuator arm32 that extends from the actuator body. Some embodiments includemultiple arms 32. Distally attached to the actuator arms 32 aresuspension assemblies 34. The suspension assemblies 34 respectivelysupport heads 36. The suspension assemblies 34 with the heads 36 arereferred to as head gimbal assemblies. The number of actuator arms andsuspension assemblies may vary depending upon the number of disks anddisk surfaces utilized.

The head 36 can include a transducer for writing and reading data. Thetransducer can include a writer and a read element. In magneticrecording applications, the transducer's writer may be of a longitudinalor perpendicular design, and the read element of the transducer may beinductive or magnetoresistive.

In optical and magneto-optical recording applications, the head may alsoinclude an objective lens and an active or passive mechanism forcontrolling the separation of the objective lens from a disk surface ofthe disk 16. The disk 16 includes opposing disk surfaces. In magneticrecording applications the disk surface typically includes one or moremagnetic layers. Data may be recorded along data annular regions on asingle disk surface or both.

The head stack assembly 26 may be pivoted such that each head 36 isdisposed adjacent to the various data annular regions from adjacent tothe outer diameter 20 to the inner diameter 18 of the disk 16. In FIG.1, the actuator body includes a bore, and the actuator 28 furtherincludes a pivot bearing cartridge 38 engaged within the bore forfacilitating the actuator body to rotate between limited positions aboutan axis of rotation 40.

The actuator 28 can further include a coil support element 42 thatextends from one side of the actuator body opposite the actuator arms32. The coil support element 42 is configured to support a coil 44. AVCM magnet 46 may be supported by the disk drive base 12. Posts may beprovided to position the VCM magnet 46 in a desired alignment againstthe disk drive base 12. A VCM top plate 48 may be attached to anunderside of the cover 14. The coil 44 is positioned, in someembodiments, between the VCM magnet 46 and the VCM top plate 48 to forma voice coil motor for controllably rotating the actuator 28.

The head stack assembly 26 can further include a flex cable assembly 50and a cable connector 52. The cable connector 52 can be attached to thedisk drive base 12 and is disposed in electrical communication with theprinted circuit board assembly. The flex cable assembly 50 suppliescurrent to the coil 44 and carries signals between the heads 36 and theprinted circuit board assembly.

With this configuration, current passing through the coil 44 results ina torque being applied to the actuator 28. The actuator 28 includes anactuator longitudinal axis 64 which extends generally along the actuatorarms 32. A change in direction of the current through the coil 44results in a change in direction of the torque applied to the actuator28, and consequently, the longitudinal axis 64 of the actuator arms 32is rotated about the axis of rotation 40. It is contemplated that othermagnet, VCM plate, coil and magnet support configurations may beutilized, such as a multiple coil arrangements, single or double VCMplates and a vertical coil arrangement.

The disk drive 10 can also include a latch 54. The latch 54 can includea fixed portion 56 that is firmly coupled to the disk drive base 12. Thelatch 54 further includes a latching portion that is engagable withfixed portion 56 to limit rotational movement of the actuator 28.Although the latch 54 is depicted as being located in a corner of thebase, the latch 54 could be located in other portions of the disk driveand still perform its functions.

When the actuator 28 is rotated into the parked position, as illustratedin FIG. 1, the actuator 28 can include a contact member 76, which can belocated on the coil support element 42 or elsewhere, that is configureto engage a crash stop 80 in order to limit rotation of the actuator 28away from the disk 16. The crash stop 80 can be an integral part of thebase 12, or the crash stop 80 can be connected to the base 12 via afixation element 72. FIG. 1 depicts an axis of engagement 66 of thecontact member 76 and the crash stop 80 as being in line with thefixation element 72, but other constructions are also permissible. Acrash stop 80 can also be provided to limit movement of the actuator 28toward the ID 18 of the disk 16.

Data is recorded onto a surface of the disk in a pattern of concentricrings known as data tracks. The disk surface is spun at high speed bymeans of a motor-hub assembly. Data tracks are recorded onto the disksurface by means of the head 36, which typically resides at the end ofthe actuator arm 32. One skilled in the art understands that what isdescribed for one head-disk combination applies to multiple head-diskcombinations.

The dynamic performance of the HDD is a major mechanical factor forachieving higher data capacity as well as for manipulating the datafaster. The quantity of data tracks recorded on the disk surface isdetermined partly by how well the head 36 and a desired data track canbe positioned relative to each other and made to follow each other in astable and controlled manner. There are many factors that can influencethe ability of the HDD to perform the function of positioning the head36 and following the data track with the head 36. In general, thesefactors can be put into two categories; those factors that influence themotion of the head 36; and those factors that influence the motion ofthe data track. Undesirable motions can come about through unwantedvibration and undesirable tolerances of components.

During development of the HDD, the disk 16 and head 36 have undergonereductions in size. Much of the refinement and reduction has beenmotivated by consumer request and demand for more compact and portablehard drives 10. For example, the original hard disk drive had a diskdiameter many times larger than those being developed and contemplated.

Smaller drives often have small components with relatively very narrowtolerances. For example, disk drive heads 36 are designed to bepositioned in very close proximity to the disk surface. Due to the tighttolerances, vibration activity of the actuator arm 32 relative to thedisk 16 can adversely affect the performance of the HDD. For example,vibration of the actuator 28 can result in variations in the spacingbetween the head element and media. Additionally, irregular movement ofthe disk 16, or vibrations caused by unbalanced rotations, can result invariations in the spacing between the head element and the disk 16, ormedia.

In addition, as disk drive tracks per inch (TPI) increases, sensitivityto small vibrations also increases. Small vibrations can causesignificant off-track and degraded performances. For example, in manycases, variations in the spacing between the head element and media canincrease the off-track complications, and the increase in TPI compoundsthe complications and likely gives rise to data errors. These dataerrors can include both hard errors during writing and soft errorsduring reading. Moreover, vibration-induced errors become even moreapparent as the actual offset distances and overall components arereduced in size.

Each disk 16 is mounted on a rotatable hub 98 connected to the spindlemotor 22 and is secured to the rotatable hub by a disk clamp 100, asillustrated in FIG. 2. Some disk drives 10 include a plurality of disks16 to provide additional disk surface for storing greater amounts ofdata. The resulting combination is referred to herein as a motor/diskassembly or as a disk pack 102.

Multiple data storage disks 16 can be mounted on the rotatable hub 98 invertically and substantially equally spaced relations. One or morebearings 104 are disposed between a motor or spindle shaft 106 and therotatable hub 98, which is disposed about and rotatable relative to thespindle shaft 106. Electromagnetic forces are used to rotate the hub 98about the stationary shaft 106 at a desired velocity. Rotationalmovement of the hub 98 is translated to each of the disks 16 of the diskpack 102, causing the disks 16 to rotate with the hub 98 about the shaft106.

The disks 16 are rotated about the shaft 106 at a high rate of speed,and consumer demand for quicker data retrieval can result in increasedrotational speed of the hub 98 and the disks 16 to provide reduced timein accessing data. Even minor imbalances of the rotating motor/diskassembly 102 can generate significant forces that can adversely affectthe ability to accurately position the head 36 relative to the desiredtrack of the corresponding disk 16 while reading from or writing to thedisk 16. Excessive imbalance can degrade the disk drive performance notonly in terms of read/write errors, but also in terms of seek times.Excessive imbalance may result in an undesirable acoustic signature andmay even result in damage or excessive wear to various disk drivecomponents.

The inner diameter 18 of each disk 16 is slightly larger in diameterthan an outer periphery of the spindle motor hub, or rotatable hub 98,in order to allow the disks 16 to slip about the spindle motor hub 98during installation. During assembly, the disks 16 may be positioned inan inexact concentric manner about the spindle motor hub 98. In fact, insome instances, the disks 16 may be intentionally biased against thespindle motor hub 98. This inexact concentric relationship between thedisk 16 and the motor hub 98 results in the disk pack 102 becomingimbalanced. This imbalance can be manifest in at least two respects.

First, the rotating mass of each disk 16 results in a centrifugal forceradially extending in a direction from the axis of rotation 24 in aplane orthogonal to the axis of rotation 24. This can be referred to asa single plane or “static” imbalance. Second, the same centrifugal forcealso results in a moment about an axis, extending from the axis ofrotation 24, as a result of the coupling of two different planes ofimbalance, each of which are orthogonal to the axis of rotation 24. Thiscan referred to as a dual plane, two plane, or “dynamic” imbalance.

Balancing of the disk pack 102 is preferably conducted, for example, bythe manufacturer or during an assembly process, prior to shipping thedrive 10 to the consumer. Single plane balancing of the disk pack 102can include attaching one or more weights to one side of the disk pack102. Not all imbalances may be alleviated to the desired degree bybalancing within a single plane. Dual plane balancing of the disk pack102 can be achieved by attaching one or more weights at two differentelevations along the axis 24 corresponding with vertically spacedreference planes in an attempt to improve upon the potentialinadequacies of a single plane balance.

Balancing the disk pack 102 can be accomplished by attaching one or moreweights to a central portion of the disk pack 102. For example, asillustrated in FIG. 2, the disk pack 102 can have a portion that holdsthe one or more weights or to which the one or more weights attach. FIG.2 illustrates a disk pack 102 having a rotatable hub 98 that includes adisk clamp 100 having a plurality of disk clamp apertures 110 positionedcircumferentially about a central portion of the disk pack 102.

The disk clamp apertures 110 can be, as illustrated in FIG. 2,substantially equidistant from, or equally spaced about, the axis ofrotation 24. For example, a plurality of the disk clamp apertures 110can be positioned about the axis of rotation 24 on a common referencecircle having its center coinciding with the axis of rotation 24. Theplurality of disk clamp apertures 110 can also include apertures thatare positioned at different radial distances from the axis of rotation24 than others of the plurality of disk clamp apertures.

In one embodiment, the disk clamp 100 includes eight disk clampapertures 110 that are positioned about the axis of rotation 24. Thedisk clamp 100 can include between about four disk clamp apertures 110and about eight disk clamp apertures 110. In one embodiment, the diskclamp 100 can include less than four disk clamp apertures 110, and insome embodiments, the disk clamp 100 can include more than eight diskclamp apertures 110.

The disk clamp apertures 110 can be designed to be substantially thesame size, and in some embodiments, the disk clamp apertures 110 can bedesigned to have apertures of different sizes. The different sizedapertures can be positioned with different radial distances as aperturesof different sizes, or the different sized apertures can be positionedwith equal radial distances from the axis of rotation than apertures ofdifferent sizes.

When balancing the disk pack 102, one or more weights can be placedwithin one or more of the disk clamp apertures 110 in order to stabilizethe disk pack 102 during operation. One or more weights can be used tooffset imbalances that are generated during operation of the disk drive10. For example, if imbalances are created by rotational movement of thedisk pack 102 during operation of the disk drive 10, one or more weightscan be placed within disk clamp apertures 110 in order to offset theimbalance created by rotational movement of the disk pack 102.

FIG. 3 illustrates a partially exploded view that includes a disk clamp100 that can be positioned on a disk pack 102 that includes one or moredisks 16. As explained, the disk clamp 100 can include a plurality ofdisk clamp apertures 110 positioned about the axis of rotation 24. Asdepicted in FIG. 3, the disk clamp apertures 110 can be positioned withsubstantially equal radial distances from the axis of rotation 24, suchthat the disk clamp apertures 110 are positioned along a commonreference circle that has its center substantially coinciding with theaxis of rotation 24.

Each of the disk clamp apertures 110 defines a disk clamp aperture axis112 that extends substantially through the respective disk clampaperture 110. The disk clamp aperture axis 112 of each of the respectivedisk clamp apertures 110 can be substantially parallel to the axis ofrotation 24. In some embodiments, the disk clamp aperture axis 112, ofone or more of the disk clamp apertures 110 can be positioned at anglesrelative to the axis of rotation 24. For example, in some embodiments,the disk clamp aperture axis 112 can be positioned at an angle ofbetween about 20° to about 80° relative to the axis of rotation 24, andin some embodiments, the disk clamp aperture axis 112 can be positionedat an angle of between about 30° to about 50° relative to the axis ofrotation 24.

In one embodiment, the disk clamp apertures 110 are positionedsymmetrically about the axis of rotation 24. In some embodiments, thedisk clamp 100 can include disk clamp apertures 110 that are positionedasymmetrically about the axis of rotation 24. And in some embodiments,the disk clamp 100 can include some disk clamp apertures 110 that aresymmetrically about the axis of rotation 24 and other disk clampapertures 110 that are positioned asymmetrically about the axis ofrotation 24.

A fastener 114 can be provided to secure the disk clamp 100 to the diskpack 102. As illustrated in FIG. 3, the fastener 114 can be positionedto be substantially aligned with the axis of rotation 24. The fastener114 is preferably threadingly received by an internal bore in the shaft106.

FIG. 3 depicts a balance plug 120 that can be positioned in one or moreof the disk clamp apertures 110 to balance the disk pack 102. Asillustrated, the balance plug 120 is configured to be sized such that itcan be received within, and preferably through, the disk clamp aperture110. Although FIG. 3 depicts only one balance plug 120 being receivedwithin a disk clamp aperture 110, the disk pack 102 can include aplurality of balance plugs 120 that are received into at least one ofthe disk clamp apertures 110.

FIG. 4 illustrates a top view of the disk clamp 100 with a plurality ofbalance plugs 120 residing within a plurality of disk clamp apertures110. As illustrated in the embodiment depicted in FIG. 4, the disk clamp100 can include a plurality of disk clamp apertures 110 that arepositioned in symmetrical fashion about a central portion of the diskclamp 100. While the disk clamp apertures 110 are positioned insymmetrical fashion, positioning of the balance plugs 120 within selectdisk clamp apertures 110 do not need to be symmetrical.

FIG. 5 illustrates a partial cross-sectional view of a portion of thedisk pack 102 that includes a rotatable motor hub 98 and a motor orspindle shaft 106 positioned about an axis of rotation 24. The disk at102 can include a plurality of disks 16 that are secured in position bya disk clamp 100. The disk clamp 100 can include a plurality of diskclamp apertures 110 that are positioned about the disk clamp 100 at aradial distance from the axis of rotation 24.

A motor hub recess 124 can extend from a top surface 126 of the motorhub 98. As illustrated, in one embodiment, the motor hub recess 124extends into the motor hub 98 but does not extend to a bottom surface128 of the motor hub 98. The motor hub 98 can include a plurality ofmotor hub recesses 124 that are positioned about the axis of rotation.

In one embodiment, each of the plurality of motor hub recesses 124 ispositioned about the axis of partition 24 at a radial distance that issubstantially the same as others of the plurality of motor hub recesses124. The motor hub recesses 124 can be positioned symmetrically aboutthe axis of rotation, and in some embodiments, the motor hub 98 caninclude motor hub recesses 124 that are positioned asymmetrically aboutthe axis of rotation 24. The motor hub recesses 124 can be positionedabout the axis of rotation 24 such that each of the motor hub recesses124 is aligned along a common reference circle cutting its centersubstantially coinciding with the axis of rotation 24. In someembodiments, the motor hub recess 124 can extend into the motor hub 98in a direction that is substantially parallel to the axis of rotation24.

As illustrated in FIG. 5, disk clamp 100 is preferably positionedrotationally about the axis of rotation 24 such that at least one diskclamp aperture 110 is substantially aligned with at least one motor hubrecess 124. In some embodiments, this orientation will permit receipt ofa balance plug 120 into at least a portion of the motor hub recess 124through the disk clamp aperture 110.

In one embodiment, at least one of the motor hub recess 124 and the diskclamp aperture 110 includes a cross-sectional dimension that is lessthan a cross-sectional dimension of the balance plug 120. For example,in one embodiment, the motor hub recess 124 can include across-sectional dimension, which can be a diameter of the recess 124,that is less than a cross-sectional dimension, which can be a diameter,of the balance plug 120. In another example, in one embodiment, the diskclamp aperture 110 can include a cross-sectional dimension, which can bea diameter of the aperture 110, that is less than a cross-sectionaldimension, which can be a diameter, of the balance plug 120.

Accordingly, in some embodiments, when the balance plug 120 is receivedinto the disk clamp aperture 110, and in some embodiments into the motorhub recess 124, the balance plug 120 engages at least one of the diskclamp aperture 110 and the motor hub recess 124. In some embodiments, atleast a portion of the balance plug 120 is compressed or deformed,plastically or elastically, when received into the disk clamp aperture110, or when residing within the motor hub recess 124.

FIG. 6 illustrates one embodiment of the balance plug 120 that can beused in connection with embodiments described in this disclosure. Thebalance plug 120 preferably includes a cylindrical body 140 that definesa top surface 142 and a bottom surface 144. The cylindrical body 140also defines a cylindrical body axis 146 that extends through asubstantially central portion of the balance plug 120. Extending about aperiphery of the cylindrical body 140 is an outer surface 148. Alsoextending about the outer surface 148 of the cylindrical body 141 is atleast one longitudinal retainer 150 that extends in a direction betweenthe top surface 142 in the bottom surface 144.

In one embodiment, the at least one longitudinal retainer 150 extends ina direction along the outer surface 148 that is substantially alignedwith the body axis 146. In one embodiment, the direction that the atleast one longitudinal retainer 150 extends along the outer surface 148is substantially parallel to the body axis 146. In some embodiments, thebalance plug 120 can include a plurality of longitudinal retainers 150that extend about the outer surface 148 of the cylindrical body 140.

The longitudinal retainer 150 preferably extends in an outward directionfrom the outer surface 148 such that a cross-sectional dimension of thelongitudinal retainer 150 and the cylindrical body 140 is greater than across-sectional dimension of the cylindrical body 140 alone. Forexample, the longitudinal retainer 150 can have a greater radialdistance 152 that extends from the body axis 146 to an outer surface ofthe longitudinal retainer 150 than a radial distance 154 that extendsfrom the body axis 146 to the outer surface 148 of the cylindrical body140.

In one embodiment, the balance plug 120 is received within the diskclamp aperture 110 by deforming a portion of the balance plug 120.Insertion of the balance plug 120 can further be facilitated byproviding one or more chamfers 156 on the longitudinal retainer 150. Forexample, the longitudinal retainer 150 can include a chamfer 156, wherethe longitudinal retainer 150 meets at least one of the top surface 142in the bottom surface 144 of the cylindrical body 140. In oneembodiment, illustrated in FIG. 5, is received to the disk clampaperture 110. A portion of the disk clamp aperture 110 can engage tochamfer 150. This configuration can limit the movement of the balanceplug 120 within at least one of the disk clamp aperture 110 and themotor hub recess 124 and can further secure the balance plug 120 againstan inadvertent dislodging of the balance plug 120 from its desiredlocation or positioning within the disk pack 102.

In some embodiments, the disk pack 102 can have balance plugs 120 thatall have the same or substantially the same mass. In some embodiments,the disk pack 102 can have balance plugs 120 of different sizes and/orof different mass. For example, in some embodiments, the balance plugs120 can have the same size and have different masses that can bedetermined based on the desired effect that will be created wheninserted into the disk pack 102. As another example, the balance plugs120 can have different sizes and have the same mass, which can also bedetermined based on how the plug 120 will affect performance of the diskpack 102. In yet another example, the balance plugs 120 can be ofdiffering sizes and differing masses.

In one embodiment, the disk drive 10 can include a spindle hub 98 havinga top surface 126. The drive can also include a disk clamp 100, coupledto the spindle hub 98, and the disk clamp 100 can have a balance plug,or disk clamp, aperture 110 that is positioned substantially over thetop surface 126 of the spindle hub 98 such that the plug aperture 110defines an aperture axis 112 that extends through the plug aperture 110and the top surface 126. The drive 10 can also include a substantiallycylindrical balance plug 120. In one embodiment, the balance plug 120includes opposing ends 142, 144 and a substantially cylindrical outersurface 148 that defines a central axis 146 of the plug 120. The plug120 can also have a protrusion 150 along the cylindrical outer surface148 that extends between the opposing ends 142, 144 in a directionsubstantially aligned with the central axis 146. The plug 120 ispreferably sized and configured to be received through the plug aperture110.

In one embodiment, the top surface further includes at least one plugrecess 124 that is configured to receive at least a portion of thebalance plug 120 when the balance plug is received through the plugaperture 110. In some embodiments, the plug is sized such that theopposing ends of the plug are positioned below a top surface of the diskclamp 100 when the plug is received through the plug aperture 110. Theplug 120 is sized, in some embodiments, such that, when the plug 120 ispositioned through the plug aperture 110, the transitional chamber 156engages a bottom portion of the disk clamp 100. Some embodiments providethat the plug includes a transitional chamfer 156 between the protrusionand at least one of the opposing ends.

In one embodiment of the balance plug 120, the protrusion, orlongitudinal retainer 150, is substantially parallel to the body, orcentral, axis 146. In one embodiment, the protrusion 150 includes acontinuous portion extending between the opposing ends of the plug 120.In some embodiments, the protrusion 150 can be segmented or extends onlypartially between the opposing ends 142, 144 of the plug 120.

Some embodiments provide that the plug 120 consists of a single, uniformmaterial. In some embodiments, this single uniform material is apolymer. In other embodiments, the plug 120 can be made of a pluralityof materials. For example, the plug 120 can, in some embodiments, have ametal that forms the cylindrical body 140 and have a polymer overmolded,over the metal, to form the protrusions, or longitudinal retainers 150.In some embodiments, the plug can be manufactured such that the materialof the cylindrical body 140 and the material of one or more protrusions150 have differing moduli of elasticity. In another example, the plug120 can be made of two different polymers, and a polymer with a highermodulus of elasticity can form the cylindrical body 140, while a polymerhaving a lower modulus of elasticity can form one or more protrusions150. In yet another example, the plug 120 can have a polymer with alower modulus of elasticity form the cylindrical body 140, and a polymerwith a higher modulus of elasticity form one or more protrusions 150.

Some embodiments provide that the balance plug can include asubstantially cylindrical body defining a first end, a second end, asubstantially cylindrical outer surface, and a plug central axis. Insome embodiments, the plug also includes at least one protrusion thatextends along the cylindrical outer surface between the first and secondends in a direction substantially aligned with the plug central axis.

Some embodiments provide a method of balancing a disk pack in a diskdrive that can include the steps of providing a disk drive having aspindle hub 98 with a top surface 126 and providing a disk clamp 100having a balance plug aperture 110 positioned substantially over the topsurface 126 of the spindle hub 98 such that the plug aperture 110defines an aperture axis 112 that extends through a portion of the topsurface 126 and the plug aperture 110. The method further includesproviding a substantially cylindrical balance plug 120 having opposingends 142, 144 and a substantially cylindrical outer surface 148 thatdefines a central axis 146 of the plug 120 and advancing the plugthrough the plug aperture 110. In some embodiments, the plug is retainedbetween the disk clamp 100 and the spindle hub 98 by a protrusion 150along the cylindrical outer surface of the plug 120, and the protrusionpreferably extends between the opposing ends in a directionsubstantially aligned with the central axis.

The method can further provide that the top surface of the spindle hubincludes a recess that receives a portion of the plug when the plug isadvanced through the plug aperture. The method may also includeadvancing a plurality of balance plugs through the disk clamp.

The description of the invention is provided to enable any personskilled in the art to practice the various embodiments described herein.While the embodiments have been particularly described with reference tothe various figures and disclosure, it should be understood that theseare for illustration purposes only and should not be taken as limitingthe scope of the inventions.

There may be many other ways to implement the embodiments. Variousfunctions and elements described herein may be partitioned differentlyfrom those shown without departing from the spirit and scope of thedisclosure. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and generic principles definedherein may be applied to other embodiments. Thus, many changes andmodifications may be made to embodiments, by one having ordinary skillin the art, without departing from the spirit and scope of thedisclosure.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically stated, but rather “one or more.” Theterm “some” refers to one or more. Any headings and subheadings are usedfor convenience only, do not limit the disclosure, and are not referredto in connection with the interpretation of the description of thedisclosure. All structural and functional equivalents to the elements ofthe various embodiments described throughout this disclosure that areknown or later come to be known to those of ordinary skill in the artare expressly incorporated herein by reference and intended to beencompassed by the disclosure. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the above description.

1. A disk drive comprising: a spindle hub having a top surface; a diskclamp, coupled to the spindle hub, the disk clamp having a balance plugaperture that is positioned substantially over the top surface of thespindle hub such that the plug aperture defines an aperture axis thatextends through the plug aperture and the top surface; and asubstantially cylindrical balance plug, the balance plug having opposingends and a substantially cylindrical outer surface that defines acentral axis of the plug, the plug having a protrusion along thecylindrical outer surface that extends between the opposing ends in adirection substantially aligned with the central axis, the plug beingsized and configured to be received through the plug aperture.
 2. Thedisk drive of claim 1, wherein the top surface further comprises atleast one plug recess that is configured to receive at least a portionof the balance plug when the balance plug is received through the plugaperture.
 3. The disk drive of claim 1, wherein the protrusion issubstantially parallel to the central axis of the plug.
 4. The diskdrive of claim 1, wherein the plug is sized such that the opposing endsof the plug are positioned below a top surface of the disk clamp whenthe plug is received through the plug aperture.
 5. The disk drive ofclaim 1, wherein the plug comprises a transitional chamfer between atleast one of the opposing ends and the protrusion.
 6. The disk drive ofclaim 5, wherein the plug is sized such that, when positioned throughthe plug aperture, the transitional chamfer engages a bottom portion ofthe disk clamp.
 7. The disk drive of claim 1, wherein the protrusioncomprises a continuous portion extending between the opposing ends ofthe plug.
 8. The disk drive of claim 1, wherein the plug comprises auniform material.
 9. The disk drive of claim 8, wherein the materialcomprises a polymer.
 10. The disk drive of claim 1, wherein the plugcomprises a plurality of materials.
 11. The disk drive of claim 10,wherein the protrusion comprises a material having a different modulusof elasticity than other materials of the balance plug.
 12. The diskdrive of claim 1, wherein the plug comprises a plurality of protrusionspositioned about the cylindrical outer surface, each of the plurality ofprotrusions having a radial dimension from the central axis that isgreater than a radial dimension of the substantially cylindrical surfaceof the plug.
 13. The disk drive of claim 1, wherein the plug comprisesfrom two to six protrusions positioned about the cylindrical outersurface.
 14. A balance plug of a disk drive, the balance plugcomprising: a substantially cylindrical body defining a first end, asecond end, a substantially cylindrical outer surface, and a plugcentral axis; and a protrusion extending along the cylindrical outersurface between the first and second ends in a direction substantiallyaligned with the plug central axis.
 15. The plug of claim 14, whereinthe protrusion is substantially parallel to the central axis of theplug.
 16. The plug of claim 14, wherein the plug comprises atransitional chamfer between the protrusion and at least one of thefirst and second ends.
 17. The plug of claim 14, wherein the protrusioncomprises a continuous portion extending between the first and secondends of the plug.
 18. The plug of claim 14, wherein the plug comprises auniform material.
 19. The plug of claim 14, wherein the materialcomprises a polymer.
 20. The plug of claim 14, wherein the plugcomprises a plurality of protrusions positioned about the cylindricalouter surface, each of the plurality of protrusions having a radialdimension from the central axis that is greater than a radial dimensionof the substantially cylindrical surface of the plug.
 21. The plug ofclaim 14, wherein the plug comprises from two to six protrusionspositioned about the cylindrical outer surface.
 22. The plug of claim14, wherein the plug comprises a plurality of materials.
 23. The plug ofclaim 22, wherein the protrusion comprises a material having a differentmodulus of elasticity than other materials of the balance plug.
 24. Amethod of balancing a disk pack in a disk drive, the method comprising:providing a disk drive having a spindle hub with a top surface;providing a disk clamp having a balance plug aperture positionedsubstantially over the top surface of the spindle hub such that the plugaperture defines an aperture axis that extends through the top surfaceand the plug aperture; providing a substantially cylindrical balanceplug having opposing ends and a substantially cylindrical outer surfacethat defines a central axis of the plug; advancing the plug through theplug aperture; and retaining the balance plug between the disk clamp andthe spindle hub by a protrusion along the cylindrical outer surface ofthe plug, the protrusion extending between the opposing ends in adirection substantially aligned with the central axis.
 25. The method ofclaim 24, wherein the top surface of the spindle hub comprises a recessthat receives a portion of the plug when the plug is advanced throughthe plug aperture.
 26. The method of claim 24, further comprisingadvancing a plurality of balance plugs through the disk clamp.